Liquid coating composition



Patented Mar. 1935 LIQUID COATIN COMPOSITION Joseph V. Meigs, DobbsFerry, N. Y., assignor to Plastix Corporation, Wilmington, DeL, acorporation of Delaware No Drawing. Original application November 10,

1927, Serial No. 232,459. Divided and this application July 14, 1932,Serial No. 622,459

3 Claims. (01. 1s4 26) This invention relates to artificial resins,especially to carbohydrate phenol resins and intended for use in themanufacture of molded or pressed articles, impregnated substances orstruc- 5 tures, or varnishes, or for other purposes for which productsof this general type are used.

One of the objects of the invention is to provide resinous productspossessing mechanical strength of a high order together with anincreased resistance to water and improved electrical insulatingproperties under conditions involving the presence of water. Anotherobject is to increase the speed with which such resins may be hardenedor rendered infusible. These and other objects Will be more fullyhereinafter described.

In the preferred form of the present invention I use the primary resins,that is the resins at the soluble and fusible stage, made as describedin my U. S. Patent No. 1,593,342, issued July 20, 1926, and in mycopending application Serial No. 92,- 640, filed March 5, 1926 nowPatent 1,868,215; although I may use other resins, as for example, theprimary resins described in my copending applications Serial No.517,721, filed November 25,

1921 now Patent 1,845,314; Serial No. 575,648, filed July 17, 1922 nowPatent 1,832,038; Serial No. 617,399, filed February 6, 1923 now Patent1,801,052; or Serial No. 4,117, filed January 22, 1925 now Patent1,801,053; or fusible and soluble carbohydrate-phenol resinsincorporating fatty acids or oils as described in my copendingapplication Serial No. 161,468, filed January 15, 1927 now Patent1,868,216.

In carrying out the invention in its preferred form, I select arelatively brittle, fusible carbohydrate phenol resin and treat it witha suitable proportion of a reactive metallic basic body, as for example,five to twenty-five per cent by Weight of calcium hydroxide andsimultaneously with, or prior to or subsequent to this treatment Iincorporate a sufiicient proportion of hardening agent, preferablyformaldehyde or derivative thereof, to enable such resin to becomeinfusible and mechanically strong when heated. Supporting, extending orother materialof a desirable character may be incorporated at anysuitable stage of the process by various means known in the art. Suchmaterial may be fibrous, cellular, amorphous or crystalline incharacter.

The metallic basic bodies used in the present invention may be dividedinto two broad classes, viz., those freely soluble in water and thosenot freely soluble or insoluble. The former class includes thehydroxides of the alkali metals and the latter group embraces compoundsof the alkaline earth metals, the earth metals and the socalledheavy'metals. I may use, as examples of the latter group, the oxides orhydroxides of calcium, barium, aluminum,'lead, zinc, tin manganese, etc.

I may, however, use any metallic com-' pound which will be sufficientlyreactive to bring J about one or more of the improvements herein noted,although I prefer to use metallic compounds not freely soluble in Water.

The invention in its preferred form may be practiced 'by reacting afusible carbohydrate phenol resin with a diificultly water solublemetallic basic body and a formaldehyde derivative,

as for example, hexamethylene tetramine, The

mutual action of the methylene amine and'the 1 metallic compoundproduces surprising improvements, the resulting productpossessing-electrical insulating properties much superior, especiallyunder conditions involving moisture, to those characteristic of the sameresinacted on by the.

formaldehyde derivative in the absence of the metallic basic compound.

In a typical case, the insulation resistance of an infusible resinousproduct made by heating a mixture of carbohydrate phenol resin, woodflour and hexa (hexamethylene tetramine) was in' creased approximatelyten fold by including 'a' substantial proportion of calcium hydroxide inthe composition. In the instance referred to, the

value of the insulation resistance was measured.

after exposing the product to a humidity of 90 per cent for five daysand therefore constitutes a measure of the ability of the resinousproduct to withstand the action of moisture. At the same time, the valueofthe product as a dielectric insulating medium, measured in terms ofdielectric constant and phase angle difference, was im-- proved morethan one hundred per cent. Hexamethylene tetramine (hexa so-called) isan eificient hardening agent for carbohydrate phenol resins in the sensethat it-yields under suitable conditions products possessing a highorder of mechanical strength, but has-the disadvantage that it alsoproduces products-which are more susceptible to water than is desiredand V which do not, particularly under conditions involving moisture,possess as high a degree of electrical insulating value as desired forsome uses.

the ammonia therefrom, to form water 'soluble This disadvantage of hexa,when applied to carbohydrate phenol resins. is due. inmy opinion, to thepresence in such resins oi? organic acids, probably humic acids orderivatives ,thereof, whichlare capable of reacting with hexa,'o11f55,

or water decomposable products. The deleterious effect of ammonia oncarbohydrate phenol resins is readily demonstrated by actual test asdescribed in my copending application Serial No. 161,469 filed January15. 1927 now Patent 1,923,321.

I have, however, overcome this disadvantage by using a metallic compoundin conjunction with hexa, and find that this combination imparts notonly suitable mechanical strength but also electrical insulating valueand water resistance of a high order.

A possible explanation of the benefits thus obtained is that thoseconstituents of the resin which otherwise react with ammonia (or hexa)may first react with the metallic base and thus become inert towardammonia, or, the metallic base may liberate ammonia from its union withthe resin. It is also possible that the water soluble orwater-decomposable reaction products of the resin and ammonia (or hexa)may form a water insoluble addition product of a physicochemicalcharacter or a chemical character with the metallic base. Any of theseor equivalent effects are to be understood as meant by the termderivative employed in the claims. My observations appear to indicatethat electrical insulating value and water resistance are highest whenthe quantity of metallic base is at least approximately chemicallyeouivalent to the ammonia capable of being yielded by the hexa.

The advantages accruing to the use of a metallic compound in conjunctionwith a methylene amine as described may be noted by reference to thefollowing table, which refers to molded compositions containing resin,wood flour and hardening agent. In one case hexa is used in conjunctionwith calcium hydroxide; in the other hexa alone is used.

It will be seen that the composition using calcium hydroxide is vastlysuperior in magnitude of insulation resistance to the compositionwithout the metallic base. With respect to dielectric properties, sincethe product of phase angle difference times dielectric constant is aninverse measure of quality it is seen that the product containing themetallic base represents a big improvement in this matter. A certainincrease in mechanical strength should also be noted.

A further effect of the metallic compound is the color of the hardenedproducts. Those containing compounds of metals such as, for example,zinc, calcium, and the like, and a methylene amine are brown. whereas inthe absence of such metallic base the color is much darker, usuallyblack, although perhaps not quite jet. From my observations. thisbleaching effect appears to be due to a mutual action of the reac tivemetallic compound, and the methylene amine, or ammonia, on the resin.This is an important discovery in view of the demand for molded orpressed products with colors other than black.

Still another advantage due to the combined use of a metallic compoundand a hardening agent, particularly a methylene hardening agent, asapplied to a carbohydrate phenol resin, is an increase in the rate ofcuring (hardening). The metallic compound appears to activate themethylene compound. This has been observed in particular in the case ofhexa when used with lime.

The invention may be practiced in various ways. For example: (1) Afusible resin may be mixed with a metallic base, an aldehydic ormethylene hardening agent such as the methylene amine, hexamethylenetetramine, and filling material, first in a ball mill and subsequentlyon heated rolls. (2) A solution of the resin in a solvent such asalcohol may be mixed with a hardening agent, metallic base and fillingmaterial and the solvent then evaporated or distilled. (3) The resin maybe heated with ametallic base until the latter combines, in whole or inpart, with. the resin; and the resulting product then mixed with thehardening agent, and with the filling material, if used, either by thedry method, or by us ing a solvent. Other modifications will suggestthemselves to those skilled in the resin art. Such procedures will yieldcompounds suitable for molding. The filling material is generally of acomminuted nature and often cellular or fibrous,

such as wood flour, cotton flock, or other forms of cellulose.

Impregnated or coated paper or fabric is prepared by substantially thesame method, the filling material being, however, in sheet form insteadof in a comminuted condition. This diiference necessitates a somewhatdifferent technique in applying the resin to the filling material. It ispossible to heat the resin with a suitable metallic compound, dissolvesuch product in a volatile solvent, together with the hardening agent,as for example hexa, and then use the resulting varnish as animpregnating or coating medium for application to paper or fabric.Equivalent results might be obtained by preparing a paper or fabricloaded with suitable proportions of metallic base, and then impregnatingor coating such paper or fabric with a solution of resin containing anappropriate hardening agent.

For the preparation of molding material one may proceed in a typicalcase as follows:

Example 1 In a ball mill pulverize and grind together 1000 grams of aprimary carbohydrate phenol resin, such as the primary or soluble andfusible resins described in Patent No. 1,593,342, together with 120grams of calcium hydroxide and 150 grams of hexa. To this mixture add1400 grams of wood flour and continue grinding until the mixture isuniform and the wood flour particles are coated with the finelypulverized resin mixture. Pass the mixture in portions throughdifferential rolls heated to to degrees centigrade, takingcare to removeeach portion from the rolls while it is still capable of readily flowingwhen subsequently molded, When all has been compacted and amalgamated bythe hot rolls, disintegrate to a coarse or fine powder as desired andmold at a temperature of to degrees centigrade under pressure in themanner customary for hot molded or heat-set products.

I; am not limited to the precise} proportions of metallic compoundindicated. The-proportions specifically described herein "are forillustrative purposesonly. Some carbohydrate phenol resins maycontainfree sulphuric acid or other equiva lent substance used as aconverting agent in the reaction between carbohydrate and phenol, and insuch case I use more than enough metallic compound to react with suchacid converting agent. ene amine, I may, as already described,advantageously use sufficient metallic compound to be chemicallyequivalent to the ammonia or amine capable of being yielded by suchhardening agent. Nor am I limited to any particular metallic compound. Ihave obtained good results by using the more diflicultly water solublemetallic hydroxides or corresponding oxides, but I may use any metalliccompound sufiiciently basic or reactive to effeet the improvementsherein described. In some cases I can use the metallic salts of fattyacids.

I am aware of 'proposals'to neutralize mineral acid catalysts inphenolic resins by bases including metallic bases and then toheat theproduct with a formaldehyde derivative, and wish to point out that myinvention is quite different. In such procedures the mineral acid isconverted into a metallic derivative but the organic resinous con-.-

such as trioxyrnethylene, condensation products offormaldehyde andaromatic amines, and other compounds, which in conjunction with ametallic base, act, on carbohydrate phenol resins to produce productspossessing mechanical strength of a high order coupled with superiorresistance to water and improved electrical insulating properties, asherein described.

The property herein described as insulation resistance was determined inthe following manner:

The samples were 12.5 centimeters long, 1.3 centimeters wide and 1.3centimeters thick. Brass strips wrappedwith tinfoil were used aselectrodes. Each electrode consisted of two strips between which thesample was clamped. Two such electrodes were placed on each sample 2.6centimeters apart. The tinfoil along the edge of each electrode waspressed down against the surface of the sample with the dull edge of aknife in order to insure good contact with the surface. The samples wereplaced'in a humidity chamber in which the relative humidity was keptconstant at 90 per cent humidity bymeans of a sulphuric acid mixture ofthe proper specific gravity. At the end of five days, measurements ofthe electrical resistance between the electrodes on each sample weremade. The results were reported in megohms and are the resistances inmegohms between the two electrodes as de-- scribed.

When the hardening agent is a methylv neighborhoodfof "8000 poundsper-square inch or more. cc I I I have found hardening'agent forcarbohydrate phenol resins.

I have'reacted glycerine'with such 're'sinssand 1 that'glycerine maybused thereby changed fusible resins tothe infusible state. Thefollowing example may 'be'cited' as an'illustration. a Example 2 Acarbohydrate phenol resin of the type referred to as a primary resin inExample 1, was distilled until the temperature of the resin reached 230degrees centigrade. Free phenol was evolved and condensed. To theresidue,

about 16 percent of glycerine-was added and distillation continued, thetemperature of the mass rising from 214 to 260 degrees centigrade duringabout two and one half hours. At the end of this time the resin becameinfusible and resilient. 1

The slow rate of hardening noted in Example 2 suggests the applicationof this reaction in the production of resinous products that are moldedand subsequently baked toharden, i. e. in the cold molding art. In suchapplication, the glycerine or equivalent will act as a flux for themolding operation and as a hardening agent in the subsequent baking. Asis well known in the cold molding art, the molding mixtures" should beplastic during molding and it is desirable that plasticizing agentscombine chemically during the subsequent baking. It would appear thatglycerine may perform these functions. Y

While my invention in its preferred form in-,

volves the use of a metallic base in conjunction with a methylenehardening agent, I may in some cases, especially with resinous productsthe properties of which do not require the use of such hardening agent,dispense with the employment of the same. The following example is anillustration. In this example aniline with hydrochloric acid isused as aconverting agent and it is to be understood that other converting agentsmay be employed as for example sulphuric acid. v i

' Example 3 A reaction mixture consisting of Argo corn sugar (crudedextrose) 420 grams, meta-para cresol 180 com., water-100 cubiccentimeters, aniline 30 cubic centimeters, and concentrated hydrochloricacid 8 cubic centimeters was boiled under a reflux condenser for fivehours, the reflux condenser being cooled by a flow of cool water atordinary temperature. An aqueous solution and a resinous product wereformed. The latter was removed and washed with hot water. 15 grams oflead dioxide were incorporated with the washed resinous product, withoutdehydrating the latter, and the resulting mass heated. At about 140degrees F. there was a sudden coagulation. Water separated and a toughrub bery mass was produced.

.This application is a division of my copending application Ser. No.232,459 filed November metals'in a volatile solvent, and a reactivehardening agent.

2.13.. potentially reactive liquid composition adapted for coating orimpregnating, comprising ahsolutionofthereaction product of a.carbohydrate phenol resin and a compound of the 5 group consisting ofoxides and hydroxides of metalsin a volatile solvent, and a reactivemethylenehardening agent.

3. A potentially reactive liquid'composition adapted for. coating; orimpregnating, comprising a solution of thereaction product of acarbohydrate phenol resin and .a compound of the group consisting ofoxides and hydroxides of metals in a volatile solvent, and hexamethylenetetramine.

JOSEPH V. MEIGS.

